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And I'm Steve Inskeep. The Food and Drug Administration is reviewing whether the maker of the most widely used emergency contraceptive pill needs to change its label. New evidence shows the pill doesn't work to prevent pregnancy in overweight or obese women. That information has been added to the drug's label in Europe but not yet here. NPR's Julie Rovner reports.
JULIE ROVNER, BYLINE: Linda Prine is a family doctor who practices in New York City. She's also the medical director of the Reproductive Health Access Project. She says she was shocked when she learned a couple of months ago about the new findings that the emergency contraceptive sold over-the-counter as Plan B starts losing its effectiveness in women weighing as little as 165 pounds and loses it completely in women who weigh more than about 175 pounds.
DR. LINDA PRINE: I don't know that the word is really out there enough yet, and that really concerns me, because this can cost women $50 a pop to take this medication and then it doesn't work and then they're pregnant.
ROVNER: The realization that the hormone levonorgestrel doesn't actually work to prevent pregnancy after unprotected sex in overweight or obese women came as sort of an accidental finding of a much broader study. It was comparing the effectiveness of several different kinds of emergency contraceptives.
Levonorgestrel is the active ingredient in Plan B, the drug approved to be sold earlier this year without a prescription and without age restrictions after a decade-long battle. Diana Blithe is a contraceptive researcher at the National Institutes of Health and one of the authors of the study. She said the findings came as something of a surprise to the researchers.
DIANA BLITHE: And it wasn't obvious until you had enough numbers of women in a population where you have a substantial number of women who are obese to be able to really do that analysis.
ROVNER: Like in the United States, where nearly two-thirds of adult women are technically considered overweight or obese. But Linda Prine says the findings don't come as a surprise to her plus-sized patients.
PRINE: I have had many patients say to me, yeah, I got pregnant using that. So, you know, they've had the experience already of it not working.
ROVNER: Blithe says it's not clear why the drug stops working in heavier women. It might have to do with metabolism, or with the volume of the medication in the blood. And would a higher dose of the drug work? No one knows.
BLITHE: There's a possibility but it has to be tested.
ROVNER: But she says one thing is clear. Now that the effect is known, the makers of all the products containing levenorgestrel - not just Plan B but all its generic copies - should be required to tell women about it.
BLITHE: I think that it is incumbent upon American manufacturers to put that info on the label now that they're aware of it.
ROVNER: Teva, the company that makes Plan B, declined comment. But in Europe, the makers of a similar product, NorLevo, have already changed their product's label. Still, Linda Prine says that for over-the-counter products, a label change might not be enough.
PRINE: I would like to see a big sign in the drugstore myself that says warning, this medication does not work if weight is over this or BMI is over that.
ROVNER: So what should heavier women do instead if they need an emergency contraceptive? On that Blithe and Prine agree.
PRINE: I'm telling patients that, depending on their weight, I would prefer, and I recommend, that they use either a different medication for emergency contraception, a newer medication called ulipristal acetate, or Ella, or that they use a copper IUD, which is the best method of all three of them, because it works almost all the time.
ROVNER: The study found Ella also stops working for obese women, although at much higher weights than Plan B. Meanwhile, the FDA says it's reviewing the new scientific information to decide if changes to any labels are in order. Julie Rovner, NPR News, Washington.